Lifting-jack.



PATENTED FEB. 13, 1906 H. M. MARSH, LIPTING JACK. APPLICATION FILED001:. 4, 1905.

' UNTTE HUGH M. MARSH, OF GHICAGU, ILLINOIS.

LiFTme-dAoK.

Application filed October 4, 1905- Serial NO- 281,306-

following is a specification, and which are illustrated in the.accompanying drawings,

forming a part thereof.

The invention relates to a lifting-jack of that type in which alifting-bar which slides in a suitable standard is operated from an actuating-lever by means of a ratchet-and-pawl mechanism, and particularlyto such a jack which may be employed for lowering as well as raising aload. In devices of this kind there are usually provided two pawls, oneof them pivotally secured to the actuating-lever and the other, aretaining-pawl, pivotally secured to the base or standard of the device,and means are provided for controlling the movement of the pawls intoand out of engagement with the ratchet-teetlrof the lift ing-bar toobtain the required movement. As heretorore constructed, however, themechanism employed for moving the pawls into and out oi engagement withthe ratchet-bar when the device is to be used for lowering a load hasincluded mechanically-operated parts between which there is considerablefriction and which when worn by use do not move the pawls completelyinto engagement with the ratchet-teeth, and the operation of the deviceis unreliable.

The object of the present invention is to provide a jack of the typedescribed in which ing operations, and in certian details of con.

struction, all as to be hereinafter described and claimed and asillustrated in the accom panying drawings, in which- Figure 1 is a sideelevation of my improved lifting-jack, a part of the outer casing beingremoved to show the interior construction. Fig. 2 is a side elevation ofthe device with the casing intact.' Fig. 3 is a view similar toSpecification of Letters Patent.

Patented Feb. 13, 1906.

Fig. 1, but showing the parts in a different position. Fig. 4 is asectional view taken on the line 4 4 of Fig. 3; and Fig. 5 is a detailof the device, shown in. perspective.

A standard is provided for the device and is of ordinary construction,preferably having a broad base 11 to take a substantial bearing upon theground. ratchet-bar 12 slides within the standard 10 and is providedwith ratchet-teeth 13, formed upon 'one of its sides for substantiallythe whole of its length. The upper portion of the standard 10 isextended at one side, as indicated at 14, to provide a suitable supportfor the moving parts of the device and an in terior chamber 15, which isnormally closed by a cover-plate 16, removably attached to the standardby means of screws 17.

An actuating-lever 18 reaches into the chamber and is pivotally securedto the walls of the standard at 19. The outer end of this lever isformed into a tapered socket 20 for receiving a wooden bar 21, such asusually accompanies devices of this kind. A pawl 22 is pivotallyattached to the inner end of the actuating-lever 18 for en aging theratchet-teeth 13, and there is also provided the usual retaining-pawl23, this pawl being pivotally attached to the Walls 14 of the chamber 15at 24 and shown as engaging the ratchet-teeth 13 above the point ofengagement of the pawl 22.

A spring-rod 25 is provided for controlling the movement of the pawlsinto and out of engagement with the ratchet-teeth 13. As shown, it is ofa V shape, having a coil 26 of one or more turns formed at the point ofthe \l to increase its flexibility and having overturned ends 27 and 28for engaging the pawls.

mounted on that pawl, as 23, upon which the bearing-block slides, andprojecting through a slotted aperture 32 in the cover-plate 16. A link33 joins the bearing-block and the A lifting-post or turn-button,thedisposition of the parts being such that either of the extremepositions of .the bearing-block is self-sustaining. As

' shown, astop 34, projecting from the face of 13 of the lifting-postwhen the lever 18 is in the raiscdposition, as shown. It, now, the lever18 is thrown down to raise the lifting-- bar, the arms of the spring arespread be yond their normal position as the pawl 22 rises, and when thelimit of this movement I has'hee'n reached the spring will be so extendedto draw the retaining-pawl 23 into engagei'nent' with theratchet-teeth 13 to support the load, while the lever 18 is again raisedto the position shown in Fig. 1 to lower the pawl 22 for a new hold uponthe liitiitg pOst. If, however, the turn-buttmi 31 is r tated to throwthe bearing blocli 29 to its extremeupper position, as in Fig. 3, thearms of the spring 25will be separated when the lifting-pawl 22 is down.more than they would normally rest, and thus draw this pawl out ofengagement with the ratchetteeth 13. The lever 18 may now be moved downto raise the pawl 22 without raising the liftingdiar. Just before thepawl 22 reaches the limit of its upward movement, however, the spring 25becomes compressed and urges the pawls apart. The pawl 22 being freemoves into engagement with the ratchet-bar, and its continued u wardmovement raises the bar enough to re ease the pawl 23, which is thenforced back by the spring, so that the load mfay descend with the pawl22. The effect of the spring is again reversed just be fore the pawl 22reaches the limit of its downward movement, and the retainingpawl 23being free is easily drawn. into engagement with the ratchet-bar tosupport the load, after which the pawl 22 is immediately released by itscontinued dowi'iwardmovernent and is drawn back by the spring, so thatit may he raised for a new hold upon the ratchetdmr, as before, withoutraising the bar. It will. he observed that the position of the pivot 24of the pawl 23 is such that this pawl never comes into a verticalposition, so that it is always urged by gravity'into engagement with theratchet-bar and would support the load if the spring 25 should break atany time.

I'claim-as my-invention- 1. In alifting-j ack, in combination, astandard, a lever pivoted to the standard, aratchetbar in slidingengagement with the standard,

bar in sliding engagement with the standard,"

a pawl pivoted to the lever, a pawl pivoted to the standard, a springhaving one end attached to each pawl, and-means for shifting the pointof attachment of the spring on one of the pawls. 1

3. In a lifting-j ack, in combination, a standard, alever pivoted to thestandard, aratchetbar in sliding engagement with the standard, a pawlpivoted to the lever, a pawl pivoted to the standard, a pivot-block insliding engagement with one of the pawls, a spring pivotallp attached tothe block and to the other paw and means for securing the block in an adjusted position on'the pawl. I

4. In alift ingjaek, in combination, a stand ard, alever pivoted to thestandard, aratchetbar in sliding engagement with the standard,

a pawl pivoted to the lever, a pawl pivoted to' the standard, apivot-block in sliding engagement with the last-named pawl, a s ringpivotally attached to the block and to he other pawl, and means forsecuring the block in an adjusted position on the pawl.

5. In a lifting-j ack, in combination, a standard, alever pivoted to thestandard, aratchetbar in sliding engagement with the standard, a pawlpivoted to the lever, a pawl pivoted tn the standard, a pivot-block insliding engagement with one of the pawls, a turn-button pivoted to thepawl, a link connecting the turn-button and the block, and a springpivotally attached to the block and to the other pawl.

6. In a lifting-j aelr, in combination, a standard, a ratchetreciprocating in the standard, a.

pair of pawls, a lever carrying one (if the pawls, and a spring reactingbetween the two pawls and arranged to reverse its action as the leverapproaches the limitsofits move ment.

noon. M. MARSH.

Witnesses CHARLES B. GILLsoN, E. M. KLAronER.

